Choose a different download folder

Firefox will automatically download files to a default location (e.g., to the Desktop or, depending on your operating system, to a special "Downloads" folder) unless you've selected a different download folder or you've set Firefox to ask where to save every file. [1][2][3] If downloads fail or if Firefox hangs downloading files it may be related to the download location; for example, the download folder may contain a lot of images [4], may be corrupt or inaccessible [5] or the folder may no longer exist. [6][7]

Note: In cases where the "Ask me where to save files" option has been selected, the problem may be related to the last-selected download folder. Instead of choosing a download folder you can try resetting the browser.download.lastDir preference in about:config (see below).

Reset download folder

Firefox may have lost track of which folder to use for the download directory. Symptoms would include "File - > Save Page As" and the "Save Image As" and "Save Link As" right-click context menu options not functioning or nothing downloading when you select the "Save" option in the Firefox "Opening" dialog box [8][9]

The solution may be as simple as choosing a different download folder, then going back and re-selecting your preferred download settings in Firefox Tools -> Options under "General / Downloads" ("Main / Downloads" in Firefox 3.5). For example, if "Always ask me where to save files" is selected, select "Save files to" and choose a download folder, then go back and re-select "Always ask me where to save files". [10]

If you still have problems you can restore the default Firefox download folder settings as follows:

Enter about:config in the address bar. A list of preferences will appear. Scroll through the list ( or type browser.download in the Filter box) and reset any of the following preferences that have a user set status (right-click on the preference and click "Reset"):

browser.download.dir

browser.download.downloadDir

browser.download.folderList

browser.download.lastDir

browser.download.useDownloadDir

You can then change back to your preferred download folder settings, if you wish, in your Firefox options/preferences.

Choose a valid download folder in Safari Preferences - Mac

Whenever you attempt to download a file, you may see the error, <filename> could not be saved, because an unknown error occurred. (Save As.. will still work). To fix this problem on Mac OS X 10.4 and earlier, open Safari Preferences and check the "Save downloaded files to:" setting. If this is pointing to an invalid directory, it will cause downloads in Firefox to fail. Select a valid directory, such as your Desktop. Note that Safari no longer controls the default download location in Leopard (10.5). [11][12]

A user reported in this thread that also changing the location using the old, unsupported Internet Explorer for the Mac solved this problem. If you still have a copy of that application, you might try this approach.

Clear the download history

You can clear the download history to see if this resolves download issues. In the Firefox (Tools) menu, go "Downloads" and click "Clear Downloads". This will remove the stored history of downloaded files in Firefox, not the actual files that are stored on your computer.

If clearing the list doesn't help or it causes Firefox to hang or crash (or if the Downloads window is already empty), you can manually clear the download history in older Firefox versions, as follows:

Download history is now stored in the Places database, in the same file as browsing history. The downloads.sqlite file was removed in Firefox 26. The file "downloads.json" is used for paused downloads. [13][14]

Note: In older Firefox versions you could set Firefox "Privacy" options under "Tools -> Options -> Privacy / "Firefox will:" -> "Use custom settings for history" to not save a download history (by clearing the "Remember download history" checkbox) or to set Firefox to clear the download history at exit (by selecting "Clear history when Firefox closes", clicking the "Settings..." button and selecting "Download History" in the "Settings for Clearing History" window). It is no longer possible to automatically clear just the download history, although this feature has been requested (bug 838681). [15]

Change or reset actions for file types

Firefox may be set to handle certain types of files with an automatic action and sometimes it is not what you want or may result in errors. For example, Firefox may automatically open a certain file type with an application or plugin, when you would rather save the file. Check for entries related to the problem file type via "Tools -> Options -> Applications" and change the action. For more information, see File types and download actions.

Delete (or rename) the "mimeTypes.rdf" file (a new file will be created when you next start Firefox)

<filename>.exe could not be opened, because an unknown error occurred. Try saving to disk first and then opening this file.

If you see this error, delete (or rename) the mimeTypes.rdf file in the Firefox profile folder, as explained above. This will resolve an issue in which Firefox tries to open executable (exe) files, which causes this error to occur. [16][17]

Information about other download managers can be found at PluginDoc. If you find any of these plugins, remove the plugin files from the Firefox plugins folder (usually C:\Program Files\Mozilla Firefox\plugins) or disable the plugins via "Tools -> Add-ons -> Plugins". See Issues related to plugins for more information.

Disable add-ons

Problematic extensions can cause download or file-saving issues, such as nothing happening when you click a download link [25] or a missing "Save File" option in the "Opening" dialog [26] (in the latter case, press the "Enter" key as a workaround). To see if an extension is causing your problem, disable it from the Add-ons manager ("Tools -> Add-ons -> Extensions") or via Firefox Safe Mode. Since certain extensions also modify preference settings, you may also need to reset those preferences via about:config (or reset all preferences).

Temporarily disable antivirus or update security software

<filename> could not be saved, because an unknown error occurred. Try saving to a different location.

You may see the above message when you click a link to download an executable (.exe) file. This problem can be caused by a conflict with your antivirus scanner and a firewall product such as Comodo Firewall (see this Comodo forum topic for details).

Some firewalls continue to be active when disabled in the user interface, so disabling the firewall may be ineffective. As a workaround, temporarily disable your resident antivirus scanner when downloading an executable file, then re-enable it when the download is complete.

If you are using the Comodo Firewall, updating it to the latest version may resolve the issue. [27][28]

Note: PC Tools ThreatFire (formerly Cyberhawk) can also cause the message, <filename> could not be saved, because an unknown error occurred when downloading certain types of files. [29] If you cannot work around the problem or resolve it by updating the software, consider using another security product.

Disable virus scanning in Firefox preferences - Windows

In Firefox 3.0 and above, up until recently, Firefox launched your installed anti-virus program to scan files when the download completes. [30] In some cases, this causes a substantial delay or hang while the file is scanned. [31][32] In other cases, the file is not saved after the scan completes. [33][34][35] You can disable this feature by setting the preference browser.download.manager.scanWhenDone to false in about:config. [36]Note: If the Download Manager appears to be stuck scanning for viruses, try closing and re-opening the Downloads window instead of disabling the preference. [37][38]

The browser.download.manager.scanWhenDone preference is no longer available in current Firefox versions. It's still included in Firefox 24 but was removed since at least Firefox 31 (the preference is still present in SeaMonkey 2.26.1 which is based on Firefox 29). Firefox 31 includes a new feature that scans downloads and blocks those that may be malicious. To turn off this new feature, modify browser.safebrowsing.appRepURL in about:config and replace the value with an empty string. This disables application reputation checks but leaves other Safe Browsing malware protection intact. [39][40]

Enable downloads blocked by Security Zone Policy - Windows

In Firefox 3 and above, Firefox honors your Windows Security zone settings for downloading and launching potentially unsafe files from the Internet. Based on your settings, downloads of executable files (e.g., .exe or .msi) may fail and the Downloads window may contain the following message under the file name:

In Firefox 3.5 and above, the Downloads window may simply show "Canceled" after the file name.

This can occur if you have customized your Internet Options Security settings for the Internet zone, if the option, "Launching applications and unsafe files" is set to "Disable". [41][42] Depending on your Windows version, this can happen if the Internet zone Security level is set to "High" (e.g., on Windows XP). [43] You can resolve this issue as follows:

An alternate solution is to reset your Windows Internet security settings, as explained below. In Firefox 4 and above, up until recently, you could bypass the Windows security policy check by setting the preference browser.download.manager.scanWhenDone to false in about:config. [47] Note, however, that this preference is no longer available in current Firefox versions.

Reset system Internet security settings - Windows

If your Windows Internet Options, Security zone setting for "Launching applications and unsafe files" is set to "Disable", Firefox 3 will block downloads of executable files or, in Firefox 3.5 and above, it will cancel the download and show Canceled - <domain name> in the Firefox Downloads window (see above). [48] To resolve this problem, use one of the following methods.

Method 2: Set a custom level for security in the Internet zone. Go to "Control Panel -> Internet Options -> Security (tab) -> Internet" (as explained above). If security is set to "High", or if you have customized the Internet zone settings, select "Custom level..." and change the single option, "Launching Applications and Unsafe Files" from 'Disable' to 'Prompt (recommended)'.

In some cases, you may need to update, reinstall, or reset Internet Explorer to restore or customize the default Internet security settings. [51][52][53]. To reset all Internet Explorer settings, see Microsoft's articles here and here. For more help, visit a Windows forum such as Microsoft Answers, AumHa Forums or WindowsBBS.com.

Note: If executable file downloads fail from certain sites but you are able to download exe files from other sites, check in "Internet Options -> Security - > Restricted sites -> Sites" to make sure that the problem site is not in the "Restricted sites" list, as the security level for that zone is High by default. Some Security software, including Spybot S&D, add known malware sites to that listing. [54]

Other solutions

Reconfigure security software. ZoneAlarm Pro and CA Personal Firewall (formerly eTrust) include settings that can cause downloads of certain file types to fail with the message, This object has been blocked. See the article Object has been blocked for information on configuring these products to allow the download.

Check your internet connection. The download error, <filename> could not be saved, because the source file could not be read. Try again later, or contact the server administrator. can occur if the connection to the server was interrupted during the download. Make sure you are connected to the internet, then try the download again.

Reset toolbars and controls. If the dialog box prompting you to open or save a download does not appear, the issue may be a corrupt localstore.rdf file. Either delete (or rename) the "localstore.rdf" file in the Firefox profile folder or use the Firefox Safe Mode option, "Reset toolbars and controls". [55]

A systematic approach to troubleshooting can be found in the Standard diagnostic - Firefox article. Also check to see if a solution to your problem is given in one of the articles listed below.